1. Field of the Invention
This invention relates to a dual tire pressure equalizer having means to communicate its status to the driver in his cab. Preferably, the communication means includes a radio frequency transmitter on the wheel and a receiver and display device in the cab.
2. Description of Related Art Including Information Disclosed Under .sctn..sctn.1.97 to 1.99
U.S. Pat. No. 4,539,928 to Gordon R. Todhunter et al discloses a dual tire pressure equalizer and indicator. The equalizer in such devices normally has inlets from both tires, one being axial of the equalizer housing and the other being offset. A spring-pressed piston is provided in the housing, the spring urging the piston toward the axial inlet. Sealing means are provided usually in the form of a diaphragm transverse of the housing, and the piston presses the diaphragm to seat against the axial inlet when pressure is low in the chamber above the diaphragm. This seating cuts off communication between the two tires so that if one tire goes flat, they do not both go flat. A tire fill connection is provided in the housing.
Thus, in operation both tires may be filled through the fill connection by way of the chamber. Thereafter, the equalizer assures that both tires are at equal pressure to assure equal tire wear. When one tire develops a leak, the pressure in the chamber will drop and the spring will move the diaphragm to seat as described, cutting off communication.
The leak in a tire in the system described above can progress while the truck is actually speeding down the highway, and the driver will be none the wiser. Condition of the equalizer can only be known by checking its indicator when the truck is stopped.
In the prior art there have been other dual tire pressure equalizers and indicators. Examples are in the U.S. Pat. No. 2,427,445 which issued Sep. 16, 1947 to A. H. Davidson and the U.S. Pat. No. 1,882,455 which issued Oct. 11, 1932 to D. H. Spicer.
Using radio to transmit tire pressure information generally is disclosed in the U.S. Pat. Nos. 4,210,898 and 4,273,728 to Betts. Other examples are disclosed in Wang U.S. Pat. No. 5,001,457 and Karbo 4,160,234.